The present invention relates to a device and a method for writing image information onto recording material. More particularly, this invention relates to a photographic printer.
A device and method of the type to which the invention relates are known from the published European Patent Application No. EP 0 924 558 A1. This publication describes a photographic printer that is capable of exposing the image information of several images onto photosensitive material. Initially, the photosensitive material in strip-shape receives a mark for each image to be exposed using a marking means. Each mark can then be recognized by a sensor located in an output unit of the known printer. This output unit is used to provide the previously determined image information of the individual images to the photosensitive recording material. The mark applied by the marking means onto the photosensitive material serves the purpose of specifying the start of the output process for outputting the image information of an image by the output unit. If such a mark is recognized by the sensor, the output process is started according to the recognition of the mark. Image data with the image information of the individual images that are to be output onto the photosensitive material is stored in a memory and provided for each output unit as required. Transport of the photosensitive material in the known printer is stopped if the image data with image information of the next image that is to be output onto the photosensitive material is not yet available in the printer, after an image has previously been written to the material by the output unit. Thereafter, the photosensitive material is moved back both in the marking means and in the output unit until the mark of the next image that is to be written to the photosensitive material is positioned behind the sensor for recognizing the mark. Thus, after this mark has arrived behind the position of the sensor, the return transport of the photosensitive material is stopped. The printer now waits for the arrival of the missing image data. After this data has arrived, a new transport of the photosensitive material from the marking means in the direction of the output unit occurs. The output of the image information of the next image to be output is initiated through the recognition by the sensor of the previous corresponding mark, which has been moved back. Transport of the entire photosensitive material located in the printer, through the known printer, is consistently in the same direction, that is, either from the marking means in the direction of the output unit, or conversely, from the output unit in the direction of the marking means. Due to the return transport of the photosensitive material, it is, therefore, possible to keep the consumption of the unused material after the interruption for providing the image data to a minimum. However, the design of the transport mechanism of the printer disclosed in the aforesaid publication, EP 0 924 558 A1, is very elaborate.